Releasable basket and method of making thereof

ABSTRACT

A medical retrieval device includes a basket formed of two or more loops. The basket may be used to retrieve material (e.g., a urinary stone) from a body. The basket opens and closes for end-encapsulation of a stone and is strengthened by support members that interconnect the basket loops. A captured stone may be released from the basket with the basket still in the body by opening the loops.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on provisional U.S. patent application Ser.No. 60/135,876, filed on May 25, 1999.

TECHNICAL FIELD

The invention generally relates to medical devices such as retrievalassemblies for retrieving material from within a body and methods ofmaking retrieval assemblies. More particularly, the invention relates toretrieval assemblies such as baskets for retrieval of stones such asurinary tract stones, gall stones, and other biological materials.

BACKGROUND INFORMATION

Medical retrieval assemblies such as baskets generally are used toretrieve biological and foreign material from the body including stones.Such baskets may be used through an endoscope or a laparoscope, forexample.

In existing medical retrieval baskets, the contour of the basketsgenerally are round, oval, or pear-shaped, and the baskets are formed bya plurality of legs. Stones or other biological materials are capturedin the basket by moving the basket around the material to be retrievedand maneuvering the material into the basket through the space betweenthe basket legs.

After the material is captured in a known basket, it is generallydifficult to release the material from the basket if release of thecaptured material is required or indicated. The technical difficulty inreleasing material such as a captured stone is a characteristic of knownmedical retrieval baskets in general. In some patients withlong-standing clinical problems with urinary tract stones, a cicatrixmay form in the tract as a result of trauma to its lining. The stenosiscreated by the cicatrix may not be so narrow so as to interfere withinsertion of a retrieval basket while the basket is in a closedposition. However, after the basket is expanded to capture the stonethat is lodged beyond the stenotic area of the tract, the diameter ofthe basket containing the captured stone may exceed the diameter of thestenotic region of the urinary tract. Under these circumstances, releaseof the stone from the basket is a prerequisite for withdrawal of thedevice from the urinary tract. If the stone can not be released, moreinvasive, surgical approaches are required to disengage the stone fromthe basket.

Also, known baskets must be eased beyond the stone or to one side of thestone to permit entry of the stone into the basket. This maneuver can betechnically very difficult. The narrow diameter of the tract lumen,compounded by the formation of stretch resistant scar tissue in thetract at the sites of the stone can severely limit the space aroundwhich the basket can maneuver. Moreover, the tract lining may become soattenuated at the site of the stone that advancing the basket to oneside of the stone may risk rupture of the tract.

When expanded, existing baskets also generally lack dilatative strength.That is, known to baskets generally are not resistive to forcescountering basket expansion. The lack of dilatative strength in existingbaskets is usually the result of flexible basket legs which are helpfulin facilitating the entry of a stone into the basket but which decreasedilatative strength. Consequently, existing baskets generally are noteffective at dilating the tract.

SUMMARY OF THE INVENTION

In one aspect, the invention relates to medical retrieval baskets withenhanced basket strength and with features that permit bothend-encapsulation and, when indicated, release of biological material.The basic medical retrieval basket design as contemplated by theinvention is an end-encapsulation basket formed by a plurality of loops.Baskets according to the invention have several advantages over otherknown baskets. One advantage is the feature that allows stone capture byend-encapsulation. The basket is formed by a plurality of loops, theloops are joined at the basket base, and have an unattached end at thedistal portion of the basket. The basket loops are moveable between aclosed position and an open position. In the open position, the ends ofthe loops are parted. When the basket is maneuvered into a body tract tocapture material such as a stone, the basket is in a withdrawn positioncollapsed within the sheath. As the end of the sheath approaches thestone, the basket is extended from the sheath. The basket loops aremoved between a closed position and an open position where theunattached ends of the loops are parted. With the unattached ends of theloops parted, the basket is advanced directly over the stone at thefront end of the basket. The stone is end-encapsulated when the stoneenters the basket through the space created by the parted unattachedends of the basket loops. The end-encapsulation basket design obviatesthe need for passing the basket to one side of, or beyond, the stone inorder to capture the stone. The basket can “pluck” stones from embeddedregions such as the calyx of a kidney. Once the stone is captured in thebasket, the unattached ends of the basket loops are juxtaposed byreturning the basket loops to the closed position. The stone is therebycaptured and the medical retrieval device with the captured stone isremoved from the body tract.

In one embodiment of the invention, the medical retrieval devicecomprises a proximal handle, an outer sheath extending distally from thehandle and including a lumen extending therethrough from a distal end ofthe outer sheath to a proximal end of the outer sheath. An inner sheathincludes a lumen extending therethrough from a distal end of the innersheath to a proximal end of the inner sheath. The inner sheath isaxially moveable in the lumen of the outer sheath relative to the outersheath.

In this embodiment of the invention, at least two opposing loops have acollapsed position in which the loops are collapsed within the lumen ofthe inner sheath and another position in which the loops are extendedfrom the distal end of the inner sheath and out of the lumen. The loopsare joined at a base and unattached to each other at their distal ends.The loops are moveable between an open position and a closed positionwith the loops being closer together at their distal ends when in theclosed position than when in the open position to allow captures andrelease of material.

In another embodiment of the invention, the medical retrieval devicecomprises a proximal handle and a sheath extending distally from thehandle and having a lumen extending therethrough from a distal end ofthe sheath to a proximal end of the sheath. Opposing first and secondhemi-baskets structures each comprise a loop and a back stay. The firstand second hemi-baskets have a collapsed position in which thehemi-baskets are collapsed within the lumen of the sheath and anotherposition in which the first and second hemi-baskets extend from thedistal end of the inner sheath and out of the lumen. The hemi-basketsare joined at a base and unattached to each other at their distal ends.The hemi-baskets are moveable between an open position and a closedposition with the first and second hemi-baskets being closer together attheir distal ends when in the closed position than when in the openposition to allow capture and release of material.

In yet another embodiment of the invention, the medical retrieval devicecomprises a proximal handle, and a sheath extending distally from thehandle and including a lumen extending therethrough from a distal end ofthe sheath to a proximal end of the sheath. At least two opposing loopsinclude a collapsed position in which the loops are collapsed within thelumen of the sheath and another position in which the loops are extendedfrom the distal end of the sheath and out of the lumen. The loops arejoined at a base and are unattached to each other at their distal ends.The loops are moveable between an open position and a closed positionwith the loops being closer together at their distal ends when in theclosed position than when in the open position to allow capture andrelease of material. The device also comprises a base cannula and anelongated member including a first portion, a second portion, and anintermediate portion. The intermediate portion of the elongated memberis inserted between the two loops and the first and second portion ofthe elongated member is inserted through the base cannula for securingthe elongated member to the at least two loops.

At least a portion of at least the inner surfaces of the basket loopscan be modified to improve stone gripping. For example, all or a portionof the inner surfaces of the loops can be coated with an anti-slipsubstance such as a rubberized material or roughened in some manner(e.g., by serrations, abrasions, etching, etc.) to increase frictionbetween the inner surfaces of the basket loops and the capturedmaterial.

In another aspect of the invention, a method for manufacturing a medicalretrieval basket comprises removing a flat frame from a single piece ofconstruction material. The frame is symmetrical and has a first end anda second end, with the first and second ends being oppositely disposed.The frame is then folded such that the first and second ends of theframe are brought together, and the joined ends are then securedtogether.

In another embodiment of this aspect of the invention, the method forforming a retrieval assembly comprises forming a frame substantially ina plane. The frame comprises at least three loop members and at leastthree joining members connecting the loop members to define an aperturein the frame. The frame is folded to superimpose the joining members onone another to cause the loop members to form loops extending away fromthe joining members. The superimposed joining members are securedtogether.

In another embodiment of this aspect of the invention, the method formanufacturing a retrieval assembly comprises forming a firstconfiguration comprising a substantially T-shape including threemembers, each member comprising a free end. One member is positionedperpendicular to the other two members. The two members of the firstconfiguration are folded to form a first loop with an apex. Theperpendicular member at the apex of the first loop is folded to form afirst-hemi-basket including a back stay.

A second configuration is formed comprising a substantiallyT-configuration including three members, each member comprising a freeend. One member is positioned perpendicular to the other two members.The two members of the second configuration are folded to form a secondloop with an apex. The perpendicular member at the apex of the secondloop is folded to form a second hemi-basket including a back stay.

The loop of the first hemi-basket is opposed to the loop of the secondhemi-basket. The free ends of the three members of the first hemi-basketare secured to the free ends of the three members of the secondhemi-basket to form the retrieval assembly.

In yet another embodiment for manufacturing a retrieval assemblyaccording to the invention, a first loop is formed from a first lengthof wire including two ends. A second loop is formed from a second lengthof wire including two ends. The ends of the first length of wire aresecured to the ends of the second length of wire to form a retrievalassembly comprising two loops.

Another method for manufacturing a retrieval device according to theinvention features the steps of, forming a shape comprising at least twoloops, and inserting a wire comprising a first end and a second endbetween the two loops. The first and second ends of the wire are pulledthrough a lumen of a cannula. The first and second ends of the wire aresecured to a cable joined in a handle and the handle is positioned atthe proximal end of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also the drawings are notnecessarily to scale, emphasis generally being placed upon illustratingthe principles of the invention.

FIG. 1A is a plan view of a medical retrieval device according to theinvention with the basket in the open position.

FIG. 1B is a plan view of the medical retrieval device of FIG. 1A withthe basket in the closed position.

FIG. 1C is a plan view of a medical retrieval device with the basket inan intermediate position between closed (FIG. 1B) and open (FIG. 1A).

FIG. 1D shows a medical retrieval device according to the inventionincluding a distal basket, an intermediate sheath, and a proximalhandle.

FIG. 2A is a plan view of a medical retrieval device with the basket ina collapsed position within the sheath.

FIG. 2B is a plan view of the device of FIG. 2A with the basket in anopen position and extended outside of the sheath.

FIG. 2C is a plan view of the device with the basket in an intermediateposition between closed and open (FIG. 2B).

FIG. 3A is a plan view of basket loops according to the inventionillustrating a modification of the inner surface of the basket loops.

FIG. 3B is an expanded view of a section of a basket loop shown in FIG.3A.

FIG. 4A is a plan view of a basket of the invention in the closedposition illustrating second elongate members.

FIG. 4B is a plan view of a basket of the invention in the open positionillustrating second elongate members.

FIG. 4C is a plan view of a basket of the invention in the open positionillustrating rigid second elongate members.

FIG. 4D is a plan view of a basket of the invention in the closedposition illustrating rigid second elongate members.

FIG. 5A is a plan view of an embodiment of a basket according to theinvention including a lithotriptic device.

FIG. 5B is a plan view of an embodiment including a push rod.

FIG. 6 is a plan view of a device having a mesh disposed within thebasket loops.

FIGS. 7A–7D are diagrammatic representations of a clinical applicationof the device of FIGS. 2A, 2B, and 2C.

FIGS. 8A–8D are diagrammatic representations of another clinicalapplication of a device according to the invention wherein the basketloops excise a tissue.

FIGS. 9A–9E illustrate a method for constructing a basket according tothe invention.

FIGS. 9F–9G illustrate an embodiment of a method according to theinvention for joining a basket to an elongated member.

FIG. 10A illustrates an end view of an embodiment of a three loop basketaccording to the invention.

FIG. 10B illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10A.

FIG. 10C illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10A.

FIG. 10D illustrates an end view of an embodiment of a four loop basketaccording to the invention.

FIG. 10E illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10D.

FIG. 10F illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10D.

FIG. 10G illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10A.

FIG. 10H illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10A.

FIG. 10I illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10D.

FIG. 10J illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10D.

FIG. 10K illustrates an embodiment of a shape according to the inventionfor forming the basket illustrated in FIG. 10D.

FIG. 10L illustrates an embodiment of a three loop basket joined to anelongated member according to the invention.

FIG. 10M illustrates an embodiment of a four loop basket joined to anelongated member according to the invention.

FIG. 11A illustrates an embodiment of a shape for the three loop basketillustrated in FIG. 11B according to the invention.

FIG. 11B illustrates an embodiment of a three loop basket formed fromthe shape illustrated in FIG. 11A according to the invention.

FIG. 12A illustrates an embodiment of a basket including opposinghemi-baskets according to the invention.

FIG. 12B illustrates an embodiment of a shape for forming a portion ofthe basket illustrated in FIG. 12A.

FIG. 12C illustrates another embodiment of a shape for forming a portionof the basket illustrated in FIG. 12A.

FIG. 12D illustrates another embodiment of a shape for forming a portionof the basket illustrated in FIG. 12A.

FIG. 12E illustrates another embodiment of a shape for forming a portionof the basket illustrated in FIG. 12A.

FIG. 12F illustrates another embodiment of a shape for forming a portionof the basket illustrated in FIG. 12A.

FIG. 12G illustrates an intermediate step in the formation of a portionof the basket illustrated in FIG. 12A.

FIG. 12H illustrates an intermediate step in the formation of the basketillustrated in FIG. 12A.

FIG. 12I illustrates another embodiment of a hemi-basket used to formthe basket in FIG. 12A.

FIG. 12J illustrates another embodiment of a retrieval basket andelongated member according to the invention.

FIG. 13A illustrates another embodiment of an intermediate step forforming a two loop basket according to the invention.

FIG. 13B illustrates an embodiment of a two loop basket and elongatedmember formed in the step illustrated in FIG. 13A according to theinvention.

FIG. 13C illustrates an embodiment of a two loop basket and elongatedmember.

FIGS. 14A–14F illustrate various embodiments of cross-sections of wiresused to form the basket according to the invention.

FIG. 14G illustrates an embodiment of a basket loop formed from the wireillustrated in FIG. 14F.

FIG. 15A illustrates an embodiment of a basket according to theinvention.

FIG. 15B illustrates an embodiment of a shape for forming the basketillustrated in FIG. 15A according to the invention.

FIG. 16A illustrates an embodiment of a retrieval device with twosheaths according to the invention.

FIG. 16B illustrates the retrieval device illustrated in FIG. 16A withthe basket extended and open.

FIG. 16C illustrates the retrieval device illustrated in FIG. 16C with astone captured in a partially closed basket.

DESCRIPTION

Referring to FIGS. 1A and 1D, a retrieval device according to theinvention includes a retrieval assembly 10, such as a basket, a catheteror sheath 18 for introduction of the basket 10 the sheath 18. As shownin FIG. 1D, the device also includes a proximal handle 9 at the proximalend of the sheath 18, and this handle typically includes one or moreactuating mechanisms 7 (e.g., a slide, a knob, a dial, etc.) coupled tothe sheath 18 and/or the cable 20 for causing the sheath 18 and thebasket 10, under operator control, to move relative to each other tomove the basket from a collapsed position within the sheath to anextended position outside of the sheath. The cable 20 generally can beany elongate member such as a cable, wire, coil, or shaft, for example.The basket 10 includes at least two basket loops 12. Each of the basketloops 12 has an unattached end 14 and a fixed end 15 at the basket base.

The basket 10 is moveable between an open position and a closedposition. In FIG. 1A, the basket 10 is in an open position. When thebasket 10 is in the open position, the unattached ends 14 of the basketloops 12 are parted as shown in FIG. 1A. When the basket 10 is in theclosed position, as shown in FIG. 1B, the unattached ends 14 of theloops 12 are juxtaposed in that they are located close together. Thebasket 10 may assume any position between the open and closed positions.For example, the unattached ends 14 of the basket loops 12 may be partedto any intermediate position along an arc drawn by the unattached ends14 of the basket loops 12 as the loops move between the closed positionillustrated in FIG. 1B and the open position illustrated in FIG. 1A.FIG. 1C illustrates an exemplary intermediate position of the unattachedends 14 of the basket loops 12 between the open position of the basket10 and the closed position of basket 10.

The basket loops 12 may be any shape, for example, generally oval (asshown in FIG. 1A), round, oblong, or asymmetrical. The basket loops 12may be disposed in one or more planes as shown in FIG. 1A. Also, whiletwo loops 12 are shown and described herein, it is possible to constructa device with two or more loops 12 and such devices are within the scopeof the invention. For example, a device with three or four or more loops12 is possible.

Also, the length of each of the loops 12 (1 in FIG. 1B) can be the same,or one can be slightly longer than the other such that the ends 14 donot exactly align upon closure. Having one loop longer than the otherhas been shown to help in collapsing the basket to its smallest profilesuch that it fits into a sheath 18 (FIG. 2A) easier.

Referring still to FIG. 1A, in a disclosed embodiment, the basket loops12 are strengthened by support members 16. The support members 16 arestruts disposed between the two opposing basket loops 12. The supportmembers 16 or struts help to prevent scissoring of the basket loops in ahorizontal plane and add strength to the basket in a vertical plane whenthe basket is expanded. It is possible to achieve a functioning basketwithout the members 16.

Referring to FIG. 2A, in one embodiment of the invention, the fixed endsof the loops 15 at the basket base is operably attached to a first cableor elongate member 20 axially disposed within the lumen 22 of the sheath18. The basket 10, when retained within the lumen 22 of the sheath 18,is in the collapsed position. In one embodiment, the sheath is made ofan biologically inert, generally flexible material. Referring to FIG.2B, advancing the first cable 20 in the direction of the arrow extendsthe basket 10 from the end 24 of the sheath 18. In this embodiment, theelasticity of the basket loops 12 causes the loops to part at theirunattached ends 14 thereby moving the basket from a closed position toan open position. Alternatively, the sheath 18 is operably attached toan actuator 7 on the handle 9 and the sheath is axially moved over astationery basket by actuating the actuator.

The basket 10 may assume any position between a closed position and anopen position depending on the extent the basket has moved beyond theend of the sheath. For example, the basket may assume the intermediateposition, illustrated in FIG. 2C. The ends 14 of the basket loops 12 mayassume any position on an arc drawn by the unattached ends 14 of thebasket loops 12 as the basket extends from fully out of the sheath tofully withdrawn within the sheath.

In the disclosed embodiment, the basket loops 10 are made from a metalmaterial. For example, basket loop material can be specialty metals suchas 455 custom stainless steel or NiTi (“Nitinol”). Alternatively thebasket loops can be made from plastic, a composite, polymer, or othermaterial. Also, the basket loops may be formed from laminations of theabove materials. In the disclosed embodiment, the basket loops are madeof flat wire (i.e., wire that is rectangular in cross section) that isabout 0.003 to 0.005 inches thick, but may be of a round, D-shape, orother cross-sectional shape.

Referring to FIG. 3A, the basket loops can have an inner surface 11 thatis designed to maximize grip on material. In one embodiment, as shown inFIG. 3B, at least a portion of the inner surface 11 is roughened byserrations or teeth. Roughening can also be achieved on the innersurfaces by etching, points, or a variety of other means. One or more ofthe basket loops may have such a rough inner surface, and it may coverall or a portion of one or more of the inner surfaces.

Referring to FIG. 4A, in an alternate embodiment, when the basket 10 isextended from the sheath 18, the basket maintains a closed position. Inthis alternate embodiment, an end of at least one wire 32 is operablyattached to an intermediate portion 34 of at least one of the basketloops 12. The wire extends into the lumen 22 of the sheath 18 and isoperably attached by its other end to a second cable or elongate member21 disposed within the lumen 22 of the sheath 18. The second cable 21may be disposed in the same or different lumens as the first cable 20.The wire 32 is kept taut by traction on the second cable 21 supplied byan actuating mechanism at the proximal handle of the device.

With continued reference to FIG. 4A, when the second cable 21 is axiallymoved in the sheath lumen 22 in the direction indicated by the arrow,the tension on the wires 32 is increased and the ends 14 of the basketloops 12 move apart until the basket 10 is in an open position asillustrated in FIG. 4B. The position of the basket 10 may beadditionally fine-tuned by axial movement of first cable 20. The ends 14of the basket loops 12 may assume any position along an arc drawn by theends 14 of the basket loops 12 depending on the degree of tensionimparted to the wires 32 by the traction maintained on second cable 21and first cable 20.

Referring to FIG. 4C, in another embodiment of the invention, when thebasket 10 is extended from the sheath 18, the basket 10 assumes an openposition. In this embodiment, the wires 32 are formed of stiff material.To move the basket from an open to a closed position, the second cable21 is advanced in the direction of the arrow. The stiff wires 32 pushthe basket loops ends 14 closer together thereby moving the basket froman open to a substantially closed position as shown in FIG. 4D. Furtherfine adjustment to the basket can be made by axial movement of firstcable 20.

In other embodiments of the invention, the device includes two or morebasket loops and at least one wire operably attached to at least one ofthe two or more basket loops.

Referring to FIG. 5A, in another embodiment of the invention, a channel36 is longitudinally disposed within the sheath 18 and extends throughthe fixed end 15 of the basket loops into the lumen 34 of the basket 10.A ram-rod 29 or other lithotriptic device such as, for example, a laser,is longitudinally disposed in the channel 36. In operation, a stone 31is captured in the lumen 34 of the basket 10. The ram-rod 29 is advancedin the channel beyond the fixed ends 15 of the basket loops and into thelumen 34 of the basket 10 until the end 35 of the ramrod 29 abuts thestone 31. The stone 31 is then fragmented by lithotripsy. The fragmentedstones 31 are withdrawn from the tract while encapsulated in the basket.

Referring to FIG. 5B, in an alternate embodiment of the invention, afterfragmentation of the stone, or under circumstances in which it isdesirable to release the stone from the basket, the basket 10 is movedfrom the closed position to the open position. A push rod 33 disposedwithin the channel 36 is advanced into the lumen 34 of the basket untilthe end 35 of the push rod 33 contacts the stone or stone fragment 31.The push rod 33 is advanced further into the lumen 34 of the basket 10until the stone or stone fragment 31 is pushed out of the basket lumen34 through the parted ends 14 of the basket loops 12.

Referring to FIG. 6, in yet another embodiment of the invention, thebasket loops 12 have a membrane or mesh material 40 disposed within theloops 12. The basket loops 12 serve as a frame to support the mesh ormembrane. The mesh or membrane 40 is attached to the wire loop frame byany means known to one skilled in the art. In one embodiment, asillustrated in FIG. 6, the mesh or membrane 40 of the loops 12 form aconcavity so that the lumen 34 of the basket is a pocket or iscup-shaped. The mesh or membrane 40 can be formed of polymer, membrane,wire, metal, mesh, film, cloth, fabric, textile, woven material, etc.

In operation, referring to FIG. 7A, the retrieval device is insertedinto a tract 50 of the body to retrieve biological material, forexample, a stone in the gall bladder, biliary tree, ureter, kidney, orurethra. The end of the device 24 is inserted into the tract 50 whilethe basket 10 is collapsed and enclosed within the sheath 18. Referringto FIG. 7B, the basket 10 is advanced in the body tract 50 until the endof the basket 24 approaches the stone 31. As the basket approaches thestone 31, the basket 10 is extended out of the sheath and moved from acollapsed position to an open or intermediate position. The method ofopening and closing the basket does not substantially alter theoperation of the device in capturing a stone within a tract. Referringto FIG. 7C, the basket 10 is advanced further into the body tract 50until the stone 31 is captured by end-encapsulation. End-encapsulationoccurs when the stone 31 passes between the parted unattached ends 14 ofthe open basket 10. Referring to FIG. 7D, after the stone 31 ispositioned within the lumen 34 of the basket 10, the basket 10 isreturned to a closed position. The unattached ends 14 of the basketloops 12 are substantially juxtaposed entrapping the stone 31 within thebasket 10. It is not essential to the operation of the basket that theunattached ends 14 of the basket loops 12 actually meet. Forparticularly large stones, for example, the diameter of the stone willprevent juxtaposition of the unattached ends of the basket. However, theessential feature of successful end-encapsulation for stone removal issufficient contact between the inner surface of the basket loops withthe stone surface so that the stone does not inadvertently slip out ofthe basket. The retrieval device with the entrapped stone is withdrawnfrom the body tract.

Referring to FIG. 8A, in yet another embodiment of the invention, thebasket loops may be used to excise tissue (i.e., perform a biopsyprocedure), for example a polyp 70 in the lumen of the gastrointestinaltract 72. An advantage of this embodiment of the invention is that thepolyp 70 is preserved in the basket lumen following polypectomy in acondition suitable for subsequent pathological examination. In oneembodiment, the basket loops are energized, for example, at theunattached ends 14 of the basket loops 12. In operation, as shown inFIG. 8A, the retrieval device is advanced into the lumen of thegastrointestinal tract 72, preferably under endoscopic guidance, untilthe basket 10 approaches the polyp 70. The polyp is end-encapsulatedwhen the basket 10, in the open position, is advanced over the polyp asillustrated in FIG. 8B. The polyp 70 is captured within the basket lumen34 as shown in FIG. 8C, and the basket 10 is moved to a substantiallyclosed position. Sufficient energy by any means known to one skilled inthe art is applied to all portions of the basket loops 12 such as theunattached ends 14 of the loops. Alternatively, the basket loops mayhave a cutting surface to permit excision of the polyps. Sufficientenergy is applied to the basket loops to separate the polyp 70 from itsstalk. Referring to FIG. 8D, the polyp 70, detached from the body, dropsinto the basket lumen 34. The polyp 70 within the basket lumen 34 iswithdrawn from the gastrointestinal tract 72. The polyp may be removedfrom the basket for subsequent pathological analysis.

In another aspect of the invention, the basket loops are constructedfrom a single piece of material. Referring to FIG. 9A, a frame 62 iscreated from a unitary piece of material. In one embodiment, the framecan be substantially oval and symmetrical with two oppositely disposedends, 60 and 60′, two loop members 64 and 64′, and support members 16.The frame 62 is removed from a single piece of substantially flatmaterial by cutting, etching, stamping, extruding, or removing by anyother method known to one skilled in the art for constructing a templatefrom a single piece of material. Referring to a particularly preferredembodiment of the invention shown in FIG. 9B, following construction ofthe frame 62, the ends 60, 60′ of the frame 62 are brought together tosuperimpose the ends on one another as indicated by the arrows in theside view of the frame illustrated in FIG. 9C. The ends 60, 60′ are thensecured to one another thereby forming the three dimensional basketstructure illustrated in FIG. 9D with two loops. That is, the members64, 64′ become the basket loops, as illustrated in FIG. 9D. The basketis shaped by cold deformation or heat shaping.

In another embodiment, the retrieval basket 10 illustrated in FIG. 9D,made from the frame illustrated in FIGS. 9B and 9C, is joined to anelongated member as illustrated in FIG. 9F. In this embodiment, a wire104 includes a first portion 102, an intermediate portion 102′, and asecond portion 102″. Wire 104 is passed in a proximal to distaldirection through the lumen 101 of a base cannula 100, then, between theproximal ends of the two loops 12, 12′ at the base 15 of the retrievalbasket 10, and back through the lumen 101 of cannula 100 in a distal toproximal direction. The intermediate portion 102′ of the wire ispositioned between the loops 12, 12′. The wire loops 12, 12′ includingproximal ends 16 are snugged up to the base cannula 100 by pulling onthe first and second portions 102, 102′ of the mandril wire 104 in aproximal direction indicated by the arrow in FIG. 9F to form theretrieval basket 10, base cannula 100, and elongated member 20 shown inFIG. 9G. Adhesive may be added to the base cannula 100.

In an alternate embodiment of the invention, a two, three, four, or moreloop basket is formed from a unitary piece of material by cutting,stamping, or etching a frame from a unitary piece of material, or bymolding or extruding a frame. For example, referring to FIG. 10B, aframe 62 is substantially flat having three loop members, 108 a, 108 b,108 c, and three joining members 114 a, 114 b, 144 c connecting thethree loop members 108 a, 108 b, 108 c to define an aperture 112. Ajoining member is any segment on the frame that is joined to orsuperimposed on at least one another segment in the frame to form theloops of the basket. A joining member may be located at the ends of loopmembers, or anywhere along the length of a loop member. A joining membermay be an enlargement, or extension of a loop member. In a three loopembodiment of a retrieval basket 10, illustrated in FIG. 10A, the frame62, illustrated in FIG. 10B, has three joining members 114 a, 114 b, and114 c, and is folded to superimpose the joining members 114 a, 114 b,114 c on one another. By superimposing the joining members on oneanother, the loop members 108 a, 108 b, 108 c are caused to formopposing loops 12 that extend away from the joining members to form thebasket 10 illustrated in FIG. 10A. Further shape refinements of thebasket 10 are accomplished by cold deformation or heat shaping. Thejoining members 114 a, 114 b, and 114 c are gathered together to formthe fixed end 15 of the basket 10. The mid-section of each of the loopmembers 108 a, 108 b, and 108 c forms the free end 14 at the apex ofeach corresponding loop 12. In a four loop embodiment of a basketillustrated in FIG. 10D, the frame 62, illustrated in FIG. 10E has fourjoining members 114 a, 114 b, 114 c, and 114 d and four loop members 108a, 108 b, 108 c, and 108 d, and is folded to form the basket 10illustrated in FIG. 10D. The number of joining members 114 in a frame 62corresponds to the number of loops 12 in the basket 10.

The two, three, four, or more loop basket can be removed from a singlepiece of flat material, as illustrated in FIG. 10C, for a three loopframe 62, or from a single piece of flat material illustrated in FIG.10F, for a four loop frame 62. Alternatively, the two, three, four, ormore loop basket of the invention can also be formed from a frame 62constructed from one or more wires 116. As illustrated in FIG. 10G, forexample, a frame 62 is featured for a three loop basket. The frame 62has three wires 116 a, 116 b, 116 c. Each end of each of the three wires116 a, 116 b, 116 c is attached to a different end of at least one otherwire to form the frame illustrated in FIG. 10G. In an alternate methodof making a three loop basket, two wires 116 a, 116 b can be used toform the frame 62 illustrated in FIG. 10H. In a two wire configurationfor a three loop frame, one wire 116 a is bent to form joining member114 a. Each end of wire 116 b is joined to a different end of wire 1116a.

In a two wire configuration for a four loop frame, illustrated in FIG.10I, wire 116 a is bent to form joining member 114 a and wire 14 b isbent to form joining member 114 c. Each end of each of the wires 116 a,116 b is joined to a different end of the other wire. The remaining twojoining members 114 b, 114 d of the four loop frame 62 are formed wherethe wires are joined to one another.

Featured in FIG. 10J, three wires 116 a, 116 b, 116 c can be used toform a four loop frame 62. For example, one wire 116 a is bent to formjoining member 114 a Each end of each of the three wires 116 a, 116 b,116 c is joined to a different end of another wire to form the four loopframe 62 illustrated in FIG. 10J. Where the three wires 116 a, 116 b,116 c are joined is where remaining three joining members 114 b, 114 c,114 d of the frame 62 are formed.

Featured in FIG. 10K, four wires 116 a, 116 b, 116 c, 116 d can be usedto form a four loop frame 62. For example, each end of each of the fourwires 116 a, 116 b, 116 c, 116 d is joined to a different end of anotherwire to form the four loop frame illustrated in FIG. 10K. Where the fourwires 116 a, 116 b, 116 c, 116 d are joined is where the four joiningmembers 114 a, 114 b, 114 c, 114 d of the frame 62 are formed.

The frame 62 illustrated in FIGS. 10B, 10C, and 10E–10K, is folded toform the three, four, or more loop basket 10 illustrated in FIGS. 10Aand 10D, by bringing together the joining members 114 of the frame 62 toform the fixed end 15 at the base of the basket 10. In the three loopembodiment illustrated in FIG. 10L, and the four loop embodimentillustrated in FIG. 10M, the fixed end 15 of the basket base is joinedto an elongated member 20, for example, in a base cannula 100 bycrimping, gluing, or soldering by some other method known to the skilledperson.

The joining members are used merely to enhance the ease by which thebaskets are made. A frame such as a circle, oval, rectangular, or, anypolygonal frame could be used to make the retrieval assembly of theinvention.

In yet another embodiment, illustrated as frame 62 for a three loopbasket in FIG. 11A, the joining members 114 a, 114 b, 114 c of the frame62 are elongated. When the frame 62 is folded to form the basket 10illustrated in FIG. 11B, the elongated joining members 114 a, 114 b, 114c are gathered together to form the elongated member 20.

An additional feature can be added to the two loop basket embodiment toform a basket 10 with opposing hemi-basket structures 110 a, 110 b asillustrated, for example, in FIG. 12A. To form a hemi-basket, a backstay 116 c extends in a plane perpendicular to the plane of the face ofthe loop formed by members 116 a and 116 b. The ends of members 116 a,116 b, 116 c are gathered together to form the base 15 of thehemi-basket. The proximal or fixed end 15 at the base of opposinghemi-baskets 110 a, 110 b is joined to the distal end of an elongatedmember 20. The hemi-baskets 110 a, 110 b reciprocally open and close ina clam shell fashion by axial 915 movement of the elongated member 20 toextend and retract the basket 10 within the sheath lumen 22.Alternatively the sheath 18 reciprocally moves axially over the basket10 at the distal end of the elongated member 20. By either method ofmoving the basket 10 relative to the sheath 18, the opposing hemi-basketstructures 110 a, 110 b are closed when retracted into the sheath lumen22 and open when extended beyond the end of the sheath 18.

The basket 10 illustrated in FIG. 12A is formed from a substantiallyT-shape configuration 62, including three members 108 a, 108 b, 108 c,such as the configuration 62 shown in FIG. 12B. Each member 108 a, 108b, 108 c has a free end. One member 108 a is perpendicular to the othermembers 108 b, 108 c. The T-shape configuration 62 is stamped, etched,or cut from a single piece of material to form three members 108 a, 108b, 108 c.

Alternatively, two or more wires 116 can be twisted together to form theT-shape configuration 62. For example, as illustrated in FIG. 12C, twowires 116 a, 116 b are twisted together to make one twisted member 108 aand two untwisted members 108 b and 108 c of the T-shape configuration62. In FIG. 12D, two wires 116 a, 116 b are used to form the T-shapeconfiguration 62. One wire 116 a of the two wires is twisted on itselfto form one twisted member 108 a of the T-shape, while the other wire116 b passes through an end of the twisted wire 116 a to form the othertwo members 108 b, 108 c of the T-shape configuration. Alternatively,shown in FIG. 12E, three wires 116 a, 116 b, 116 c are used to form aT-shape configuration 62 with three twisted members. To make the T-shapeconfiguration 62 illustrated in FIG. 12E, a two wire 116 a, 116 bT-shape configuration like the configuration 62 illustrated in FIG. 12Cand discussed in the corresponding text, is formed initially. A thirdwire 116 c is twisted with the remaining untwisted portion of wires 116a, 116 b to form the T-shape configuration with twisted wires in each ofthe three members 108 a, 108 b, 108 c illustrated in FIG. 12E.

To form the hemi-baskets 110 a, 110 b of the retrieval basket 10illustrated in FIG. 12A, two 108 b, 108 c of the three members 108illustrated in FIG. 12G are folded to form a loop with the free ends ofthe two members 108 b, 108 c gathered together. The distal or closed end14 of the loop is formed at the intersection of the three members 108 a,108 b, 108 c of the T-shape configuration 62. The third member 108 a,that runs perpendicular to the other two members, is folded down to forma back stay as illustrated in FIG. 121. The end of member 108 a isgathered together with the ends of members 108 b, 108 c to form thefixed end 15. Further frame modifications are accomplished by colddeformation or heat shaping. When two of the hemi-basket structures 110a, 110 b are opposed, a clam shell structure results as illustrated inFIG. 12H. The free ends 15 of the loops and back stay can be attached toan elongated member 20 to form the clam shell retrieval assemblyillustrated in FIG. 12A. Alternatively, the free ends of the members ofthe T-shaped configuration can be gathered or twisted together as shownin FIG. 12J to form the elongated member 20.

A retrieval basket including two hemi-basket structures can be formedfrom the frame illustrated in FIG. 12F. In this embodiment, the frame 62is removed from a single piece of material. The frame is folded to formtwo hemi-baskets by superimposing member 21 a on member 21 b and bendingmember 120 a to make the back stay of one hemi-basket, and bendingmember 120 b to make the back stay of the other hemi-basket. Thus theapex of the two loops of the hemi-baskets are formed from 14 a and 14 b.

Another method, according to the invention, for forming a retrievalbasket including two loops is illustrated in FIGS. 13A–13C. This methodfeatures pairing two elongated loops 12 together as shown in FIG. 13A.The proximal end 109 of each of the loops 12 is attached to an elongatedmember 20 through a base cannula 100 illustrated in FIG. 13B, or othermeans, and the opposite, distal ends 14 of the loops 12 remain free.Alternatively, the proximal ends 109 of the loops 12 can be twistedtogether to form the elongated member 20, shown in FIG. 13C.

Retrieval baskets having three, four, or more loops can also be formedaccording to this method and the basket forming method illustrated inFIGS. 13A–13C is not intended to be limited to only the two loopembodiment illustrated.

Any of the wire baskets according to the invention, may use one or morewires 116 having any one of a variety of cross-sections. The ends of thewires forming the basket may extend proximally all or part of the way tothe handle to form the elongated member. For example, illustrated inFIGS. 14A–14F, the cross-section of the wires 116 may be round, oval,square, rectangular, or D-shaped. A feature of wire 116 including around cross-section, is a flattened mid-section 118, illustrated in FIG.14F. The flattened section 118 can form the distal or free end 14 of theloop, and the two end-sections 119 with round cross-sections form theremaining portions of the loop and/or all, or a portion of the elongatedmember 20 illustrated in FIG. 14G.

The inner edge 11 of any of the basket loops according to the inventionmay be roughened, for example, by serrations or teeth, as shown in FIG.9D, and FIG. 15A, or by etched surfaces, or pointed raised structures.Particles also may be applied to the inner edge 11 to improve grippingof the loops 12 on an object. One or more of the basket loops 12 mayhave such a rough inner edge 11. The roughened edge may be incorporatedinto the frame 62 when it is removed from a single piece of material,illustrated in FIGS. 9E and 15B. Alternatively, the roughened edge maybe applied after the frame 62 is constructed but before the frame 62 isfolded into a three-dimensional basket. The inner edge 11 of the loopmembers can instead or additionally be treated with an anti-slipmaterial such as a plastic composite or a rubberized coating before theframe 62 is folded into a three dimensional basket frame with loops.

In another aspect of the invention, referring to FIGS. 16A–16C, themedical retrieval device 10 has two sheaths, an outer sheath 18 and aninner sheath 19. The outer sheath has a longitudinally disposed lumen22, and the inner sheath has a longitudinally disposed lumen 22′. Theinner sheath 19 is axially disposed in the lumen of the outer sheath 18.An elongated member 20 is axially disposed in the lumen 22′ of the innersheath 19 and attached at a distal end to the basket base 15. The basket10 is moveable between an open position, illustrated in FIG. 16B whenthe basket 10 is extended beyond the distal end of the inner sheath 19and outer sheath 18, and a closed position, illustrated in FIG. 16A,when the basket 10 is retracted into the lumen 22′ of the inner sheath19. The basket 10 moves between the open and closed position either byaxial movement of the elongated member 20 relative to a stationarysheath 19, or by axial movement of the inner sheath 19 over the basket10 relative to a stationary elongated member 20 as described above.

In a two sheath embodiment, the basket 10, illustrated in FIG. 16A, isadvanced in its closed position adjacent a stone 31. The basket 10,illustrated in FIG. 16B, is extended from the distal end of the innersheath 19 and outer sheath 18, and opened. The stone 31 is captured bythe basket 10 and the inner sheath 19 is moved relative to the basket 10to collapse the basket 10 around the stone 31 thereby grasping the stone31 more firmly. The basket 10, stone 31, and inner sheath 19 areretracted into the lumen 22 of the outer sheath 18 and the medicalretrieval device 8 is removed from the body.

Variations, modifications, and other implementations of what isdescribed herein will occur to those of ordinary skill in the artwithout departing from the spirit and the scope of the invention asclaimed. Accordingly, the invention is to be defined not by thepreceding description but instead by the spirit and scope of thefollowing claims.

1. A medical retrieval device comprising: a proximal handle; a sheath extending distally from the handle and including a lumen extending therethrough from a distal end of the sheath to a proximal end of the sheath; opposing first and second hemi-baskets, each hemi-basket comprising a loop and a back stay, the opposing first and second hemi-baskets having a collapsed position in which the first and second hemi-baskets are collapsed within the lumen of the sheath and another position in which the first and second hemi-baskets extend from the distal end of the inner sheath and out of the lumen, the first and second hemi-baskets being joined at a base and unattached to each other at their distal ends, the first and second hemi-baskets being moveable between an open position and a closed position with the first and second hemi-baskets being closer together at their distal ends when in the closed position than when in the open position to allow capture and release of material.
 2. The medical retrieval device of claim 1, wherein the back stay of at least one hemi-basket extends in a first plane and the loop of the at least one hemi-basket extends in a second plane, the first and second planes being substantially perpendicular to each other.
 3. The medical retrieval device of claim 1, further including an elongated member joined to the base.
 4. The medical retrieval device of claim 3, wherein the elongated member is disposed within the lumen of the sheath.
 5. The medical retrieval device of claim 3, wherein the elongated member is configured to assist in transitioning the first and second hemi-baskets between the open and closed positions through axial movement of the elongated member relative to the sheath.
 6. The medical retrieval device of claim 1, wherein the sheath is configured to assist in transitioning the first and second hemi-baskets between the open and closed positions through axial movement of the sheath relative to the first and second hemi-baskets.
 7. The medical retrieval device of claim 1, wherein the loop and the back stay of at least one of the hemi-baskets are formed of the same piece of material.
 8. The medical retrieval device of claim 7, wherein the loop and the back stay of the at least one hemi-basket are formed by one of stamping, etching, and cutting.
 9. The medical retrieval device of claim 1, wherein the loop and the back stay of the at least one hemi-basket are formed from a substantially T-shape configuration.
 10. The medical retrieval device of claim 1, wherein at least one of the first and second hemi-baskets comprises at least two wires.
 11. The medical retrieval device of claim 10, wherein at least one of the loop and the back stay of at least one of the hemi-baskets comprises at least two wires.
 12. The medical retrieval device of claim 11, wherein the back stay of the at least one hemi-basket comprises two wires twisted together.
 13. The medical retrieval device of claim 12, wherein the loop of the at least one hemi-basket comprises untwisted lengths of the two wires.
 14. The medical retrieval device of claim 13, wherein the loop of the at least one hemi-basket comprises a third wire twisted with the two untwisted lengths of the two wires.
 15. The medical retrieval device of claim 10, wherein the back stay of at least one of the hemi-baskets comprises a first wire twisted on itself and the loop of the at least one hemi-basket passes through an end of the first wire.
 16. The medical retrieval device of claim 1, wherein free ends of the loop and back stay of at least one of the first and second hemi-baskets are twisted together to form an elongated member.
 17. The medical retrieval device of claim 1, wherein free ends of the loop and back stay of at least one of the first and second hemi-baskets extend substantially adjacent to each other proximal the base of the at least one hemi-basket.
 18. A medical retrieval device comprising: a proximal handle; a sheath extending distally from the handle and including a lumen extending therethrough from a distal end of the sheath to a proximal end of the sheath; and opposing first and second hemi-baskets, each hemi-basket comprising a loop and a back stay, the first and second hemi-baskets being joined at a base and moveable in a clam shell fashion between an open position and a closed position with the first and second hemi-baskets being closer together at their distal ends when in the closed position, wherein the back stay of at least one hemi-basket extends in a first plane and the loop of the at least one hemi-basket extends in a second plane, the first and second planes being substantially perpendicular to each other.
 19. The medical retrieval device of claim 18, wherein the loop and the back stay of the at least one hemi-basket are formed from a substantially T-shape configuration.
 20. The medical retrieval device of claim 18, wherein at least one of the first and second hemi-baskets comprises at least two wires.
 21. The medical retrieval device of claim 18, wherein at least one of the loop and the back stay of at least one of the hemi-baskets comprises at least two wires.
 22. The medical retrieval device of claim 21, wherein the back stay of the at least one hemi-basket comprises two wires twisted together.
 23. The medical retrieval device of claim 22, wherein the loop of the at least one hemi-basket comprises untwisted lengths of the two wires.
 24. A medical retrieval device comprising: a proximal handle; a sheath extending distally from the handle and including a lumen extending therethrough from a distal end of the sheath to a proximal end of the sheath; and opposing first and second hemi-baskets, each hemi-basket comprising a loop and a back stay, the first and second hemi-baskets being joined at a base and moveable in a clam shell fashion between an open position and a closed position with the first and second hemi-baskets being closer together at their distal ends when in the closed position, wherein the back stay of at least one hemi-basket comprises two wires twisted together and the loop of the at least one hemi-basket comprises untwisted lengths of the two wires.
 25. The medical retrieval device of claim 24, wherein the loop and the back stay of the at least one hemi-basket are formed from a substantially T-shape configuration.
 26. The medical retrieval device of claim 24, wherein free ends of the loop and back stay of at least one of the first and second hemi-baskets are twisted together to form an elongated member.
 27. The medical retrieval device of claim 24, wherein free ends of the loop and back stay of at least one of the first and second hemi-baskets extend substantially adjacent to each other proximal the base of the at least one hemi-basket.
 28. A medical retrieval device comprising: a proximal handle; a sheath extending distally from the handle and including a lumen extending therethrough from a distal end of the sheath to a proximal end of the sheath; and opposing first and second hemi-baskets, each hemi-basket comprising a loop and a back stay, the first and second hemi-baskets being joined at a base and moveable in a clam shell fashion between an open position and a closed position with the first and second hemi-baskets being closer together at their distal ends when in the closed position, wherein the back stay of at least one of the hemi-baskets comprises a first wire twisted on itself and the loop of the at least one hemi-basket passes through an end of the first wire.
 29. The medical retrieval device of claim 28, wherein the loop and the back stay of the at least one hemi-basket are formed from a substantially T-shape configuration.
 30. The medical retrieval device of claim 28, wherein the back stay of at least one hemi-basket extends in a first plane and the loop of the at least one hemi-basket extends in a second plane, the first and second planes being substantially perpendicular to each other.
 31. The medical retrieval device of claim 28, wherein free ends of the loop and back stay of at least one of the first and second hemi-baskets are twisted together to form an elongated member.
 32. The medical retrieval device of claim 28, wherein free ends of the loop and back stay of at least one of the first and second hemi-baskets extend substantially adjacent to each other proximal the base of the at least one hemi-basket. 